I was chatting with an intimate friend and somehow we started talking about God. The thing is, she believes in God, and I do not. Though I don't want to force her to accept my views, surely I wanted to make her question her own thoughts. This is how I went about it.

Me : You don't believe me?

She: Who said I don't believe you? Why that doubt?

Me : Just a question.

She: I believe you... Truly

Me : Haha . Okay, say, do you believe in God?

She: Wow! I too thought about asking this question to you. I believe. You?

Me : Unfortunately, no.

She: I had guessed...Why?

Me : You guessed? Good! In the name of God so much cruelty is in this world. And the concept of God, sure, it has practical utility, but organized religion misuses that concept to deceive many people. These people, in turn, after being decieved, worsen this place.

She: Hmmm...That's right...There is a power, being invisible...Said to be a power of god. What do you say?

Me :I never experienced any external power in my life. So all I believe in is myself and science. All else is darkness

She: Hmmm...

Me : Why do you believe in God?

She: I don't know exactly...Some situations made me believe God. But I don't believe too much, only for a certain extent.

Me : That's what most people say, they don't know why. I too was like that. Then I thought, and read. And then I understood. I believed in the god-myth because I was instructed to do so by my environment.

She: Yeah...Maybe for me, effect from environment too!

Me : You are saying you believe only to a certain extent. Say, 70%. What about the other 30%? Is that part disbelief?

She: Maybe...Yeah.

Me : Disbelief is doubt, right? Do you really believe in God?

She: If you ask like this...am confused what to say...I am in middle stage, not believing completely and not disbelieving also.

Me : Okay... Do you believe in ghosts?

She: Ghosts...! No...But I have a small fear of them when someone talks about them for too long. But actually, no, I don't believe in ghosts.

Me : Why?

She: They do not exist.

Me : Why do you say so?

She: I heard about it.

Me : You believe whatever you hear?

She: No! Not at all! Then do you think ghosts exist?

Me : I'll tell my idea later. You believe gods exist, as invisible entities. But at the same time you say, ghosts don't exist, which are also supposed to be invisible. How do you explain that?

She: Don't know how to explain... :(

Me : Yeah, that's inconsistency in thought. It is logical if you believe both gods and ghosts exist. It is logical if you believe both gods and ghosts do not exist. But you are saying, gods exist, ghosts do not! Can you see more clearly now?

She: Yeah...so?

Me : Can you imagine the reason for this inconsistency in your mind? Hint: it's not your problem

She: Don't know. maybe the environment where I grew up.

Me : Exactly. Elders say: "there are no ghosts!" Because they don't want you to cry. Elders say: "there is god to help you when you are in trouble, when someone cheats you, etc, etc" They tell this because that's what their elders used to say to them! These mild suggestions become firm beliefs with time!

She: Yeah...I think so. But then ghosts and gods come under the same category?

Me : See it from another view. There are theives in this world. To control them there is police. If there is no theif, then certainly there won't be any police, right?

She: Right...so?

Me : It is the same with God and ghost. If there are ghosts, like thieves, then in all possibility there will be gods, to control them like the police. But, if as you say there are no ghosts, then surely there is no need for gods to exist! Gods and ghosts are much related if you think about them!

She: Ohh...I didn't think so much...Maybe you are right...

Me : Well, think it over! Bye

She: Bye

I don't think I convinced her much, but surely I must have made her question her own beliefs.I think carefully crafted simple questions and analogies can initiate change. What similar strategies have you used to make people question their own beliefs about God?

Ancient man believed god was responsible for a lot of things that were happening around him - cause he didn't know any better.

Sun rise and sunset, eclipses, rain, fire... and so on - until man understood the scientific reasons behind these phenomenon, they were all attributed to god.
As scientific understanding improved, man started to take credit away from god for those things. He could understand, and in most cases - cause them himself or at least predict them.

But understand that the reverse has never happened... Man has never - after having found an explanation for something - gone back and said "oh... I was wrong about that. I thought I understood how xyz happens, but turns out I was wrong. So I'm going to say god causes it".

So, effectively, "it's created by god" is merely an euphemism for "i don't understand how it works".
And unfortunately, human perception is very limited relative to the universe, so there will be no dearth of things we don't understand.